From: Philipp Hofmann <phil@...126.de>
Date: 2009-11-09T07:02:45+09:00
Subject: wxRuby + rcairo ... are driving me mad.


How is it possible to use Wx::GraphicsContext#get_native_context with
rcairo? Let me quote the wxRuby documentation from

  http://wxruby.rubyforge.org/doc/graphicscontext.html#GraphicsContext_getnativecontext

  "Returns the native context (CGContextRef for Core Graphics, Graphics
  pointer for GDIPlus and cairo_t pointer for cairo)." [1]

Is there a way to cast the data the cairo_t pointer points to into a
Cairo::Context? Everything I tried resulted in an 'called on
terminated object' error. Well, at least the reasonable attempts.

--- snip ---------------------------------------------------------

#!/usr/bin/env ruby                                                                 

require 'rubygems'
require 'wx'
# require 'cairo'                                                                   

include Wx

class MyCanvas < Window
  def initialize(parent)
    super(parent)
    timer = Timer.new(self, 1000)
    evt_paint do
      paint do |dc|
        puts "painting on #{dc}"
        gdc = GraphicsContext.create(dc)
        # whatever I do with the native context, I get                         
        # method '...' called on terminated object                                  
        gdc.get_native_context
      end
    end
    evt_timer(1000, :refresh)
    timer.start(100)
  end
end

class MyFrame < Frame
  def initialize
    super(nil, -1, 'MyTitle', :style => DEFAULT_FRAME_STYLE)
    canvas = MyCanvas.new(self)
  end
end

class MyApp < App
  def on_init
    frame = MyFrame.new
    frame.show(true)
  end
end

myapp = MyApp.new
myapp.main_loop

--- snip ---------------------------------------------------------

Any help is highly appreciated
Best phil